Mid-depth South Atlantic ocean circulation and chemical stratification during MIS-10 to 12: implications for atmospheric CO 2

• Main Authors: Dickson, A. J., Leng, M. J., Maslin, M. A.
• Other Authors: Environmental Change Research Centre, Department of geography, NERC Isotope Geosciences Laboratory, British Geological Survey (BGS)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2008
• Subjects: [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces; environment; [SDU.STU]Sciences of the Universe [physics]/Earth Sciences; Southern Ocean; North Atlantic Deep Water; North Atlantic; South Atlantic Ocean
• Online Access: https://hal.science/hal-00298224; https://hal.science/hal-00298224/document; https://hal.science/hal-00298224/file/cpd-4-667-2008.pdf

International audience A detailed record of benthic foraminifera carbon isotopes from the South East Atlantic margin shows little glacial-interglacial variability between MIS-12 to MIS-10, suggesting that Glacial North Atlantic Intermediate Water (GNAIW) consistently penetrated to at least 30° S. Millennial-scale increases in either the mass or flux of GNAIW over the core site occur alongside reductions in Lower North Atlantic Deep Water recorded in North Atlantic sediment cores and show that the lower and intermediate limb of the Atlantic deepwater convective cell oscillated in anti-phase during previous glacial periods. In addition, a 500 yr resolution record of the Cape Basin intermediate-deep ? 13 C gradient shows that a reduction in deep Southern Ocean ventilation at the end of MIS-11 was consistent with a modelled CO 2 drawdown of ~21?30 ppm. Further increases in the Southern Ocean chemical divide during the transition into MIS-10 were completed before minimum CO 2 levels were reached, suggesting that other mechanisms such as alkalinity changes were responsible for the remaining ~45 ppm drawdown.